After having experienced 350 surgical cases of vestibular schwannoma, the following are lessons that we have learned to remove the tumor successfully : 1. Haste makes waste 2. Quick and slow 3. Believe and doubt 4. No touch, no traction 5. Fear and fear not 6. Remember facial nerve always 7. Debulk first and see nerves 8. Avoid blood staining of nerves 9. Respect arachnoid 10. Retreat at an unusual difficulty

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Seventy-four patients with bilateral acoustic schwannomas (AS) registered in a nationwide study from 1986 to 1987 were studied. Kaplan-Meier analysis indicated that overall 10- and 20-year survival rates following diagnosis of NF2 patients were 67% and 38%, respectively. Early onset of the initial symptom significantly compromised survival. The AS volume was measured on CT or MRI and retrospectively studied in 27 patients (54 AS). In natural course, it was difficult to predict tumor growth. After treatments, clinical factors that significantly contributed to the tumor growth were younger symptom onset, association of intracranial meningioma, and larger tumor volume before the treatment. Regrowth rate was low after gamma-knife treatment and no recurrence after total tumor removal. Large AS in patients with earlier symptom onset or intracranial meningioma require total removal. During the past 5 years, 243 NF2 patients were followed in 78 institutes : 49 without treatment, 125 with surgical resection, 47 with radiosurgery, and 22 with resection and radiosurgery. Opinions about treatment of NF2 patients from 67 institutions were analyzed. Strategies for AS were divergent. Large AS or AS showing tumor growth on serial MRI require treatment. Total removal is desirable. Gammaknife radiosurgery is effective for small AS. The first side of bilateral AS need early treatment. The second side of AS should be treated after hearing deterioration occurs in this side. With brainstem or cerebellar signs present, however, the second side requires early resection as well.

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Skull base meningiomas may involve the cranial nerves, main vessels and vital brain structures. Because the biological behavior of skull base meningiomas is the same as for meningiomas at common locations, the ideal management of skull base meningiomas is total resection with dural attachment. However, radical resection is impossible or not preferable because of the risk of severe operative complications in some cases. The goal of skull base meningioma removal should be determined in each case based on a precise analysis of the meningioma's extension pattern.

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Once considered to be a rare tumor, primary CNS lymphoma (PCNSL) now afflicts approximately 300 people in Japan each year. PCNSEs completely regress with corticosteroid or irradiation, but soon recur. Median survival time of PCNSL patients has been reported to be 10 to 18 months by radiotherapy alone. The current treatment recommendation is systemic high-dose methotrexate followed by whole cranial irradiation treatment. This strategy produces a response rate of 80-90% and an MST of more than 30 months. However, improved survival overshadows treatment efficacy especially in the elderly patients over 60 years of age in whom delayed therapy-related neurotoxicity is observed frequently. Multi-institutional prospective trials will ensure the establishment of a consensus for therapy of this disease based on age and other prognostic factors.

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Among the significant prognostic factors such as the patient's age, performance status, or tumor histopathology, the most important prognosticator for glioma patients is the degree of tumor removal. On the other hand, surgical removal should not induce aggravation of the patient's performance status. As a result, surgical planning for glioma should be carefully considered. However, there is no standard guide for preoperative planning at present. In this study, we tried to divide 390 gliomas into 5 stages according to the difficulty of surgery and then analyzed the relation between removal rate and each stage. The results demonstrated that the stage correlates with both the removal rate and the patient's survival. This grouping can be useful to discuss the feasibility of surgical planning among multiple neurosurgical institutions.

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Within the context of embryogenesis, and particularly with regard to prosencephalic cleavage, we describe the anatomical characteristics of holoprosencephaly, which results from a disorder of ventral induction. To interpret morphogenesis in this anomaly, it is important to know the difference between the hemispheric telencephalon (hemispheric brain) and the holospheric telencephalon (holospheric brain). While the hemispheric brain represents normal development of the paired neocortical primordium (telencephalon 'totopar'), the holospheric brain, which is an essential feature of holoprosencephaly, results from failed development of the neocortex, which may originate from a single or unpaired primordium. Thus, holoprosencephaly shows an undivided telencephalon 'totopar' (supralimbic lobe), where the neocortex shows midline continuity in the more rostral part of the telencephalon. In addition, while the dorsal cyst is usually absent in lobar holoprosencephaly, the dorsal sac, which represents the unfolded diencephalic roof plate, covers the dorso-caudal aspect of the prosencephalic ventricle. These anatomical features, such as midline continuity of the cerebral neocortex and an unfolded diencephalic roof plate, are common to the holospheric brain. On the other hand, callosal defect, which results from maldevelopment of the telencephalon 'impar' (medium) after complete hemispheric cleavage, may show an elevated roof of the third ventricle. Marked dilatation of the third ventricle with absent or hypoplastic falx cerebri is called primary interhemispheric cyst, and its configuration mimics holoprosencephaly with a dorsal cyst. Since a primary interhemispheric cyst consists of an elevated but folded diencephalic roof plate (roof of the third ventricle) in the hemispheric brain, it should be differentiated from holoprosencephaly.

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Congenital hydrocephalus includes both fetal hydrocephalus and postnatal hydrocephalus due to various prenatal pathological conditions. With the recent advancement of the neuro-imaging techniques applied for prenatal diagnosis, neurosurgeons have come to notice patients with congenital hydrocephalus more frequently than previously. In the present report, we described standard treatment for and prognostic factors of this disease. Cerebrospinal fluid (CSF) shunt is the standard procedure in children with a body weight more than 2,000 g. In the case of a baby with insufficient body weight, CSF drainage via a miniature Ommaya reservoir can be applied tentatively before installation of CSF shunt. Endoscopic third ventriculostomy is not recommended especially for neonates with congenital hydrocephalus. Fetal examination by neuro-imagings is crucial to arriving at a proper diagnosis, because postnatal prognosis differs a great deal among various types of associated central nervous system anomalies. Congenital hydrocephalus uncomplicated by significant anomalies of the central nervous system has a relatively favorable prognosis. Postnatal prognosis is poor in hydroanencephaly, semilober or alober holoprocencephaly, encepahlocele with extrusion of the cerebral ventricle and severe dysgenesis of the cerebellar vermis in Dandy-Walker syndrome. There are other prognostic factors involved in the hydrocephalic condition itself. For example, a cerebral mantle thinner than 2 cm, or early prenatal diagnosis of hydrocephalus are poor prognostic factors. Knowledge of these data can help neurosurgeons perform standard treatment of this disease in consideration of evidence-based medicine (EBM). At the time of diagnosis, however, parents become very confused and depressed and, if they are informed of even standard treatment and of the most likely postnatal prognosis solely according to EBM, they tend to seek termination of pregnancy or to refuse postnatal treatment for the child. To avoid such a situation so disadvantageous for the patient, counseling should be introduced as one of the clinical applications of narrative-based medicine (NBM). When the hydrocephalus is diagnosed before the 22nd gestational week, counseling can help the parent make a deeply considered decision on termination of the pregnancy. When it is diagnosed at the 22nd gestational week or after (the legal termination is prohibited in this period), counseling can help the parents to accept and raise their child with congenital hydrocephalus. We know that clinical data based on the clinical evidence (EBM) are essential for treatment of this disease. However, with the introduction of the practical application of NBM, we can provide more satisfactory and better medical treatment for children with congenital hydrocephalus and more support for their family.

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Problems of fetal hydrocephalus and adult patients with congenital hydrocephalus continue to be unsolved. Recently 55% of congenital hydrocephalus is diagnosed prenatally as fetal ventriculomegaly, as result of advances in prenatal imaging techniques. The result of the nation-wide survey performed in 1999 shows that fetal ventriclomegaly include various disorders, such as simple hydrocephalus, myelomeningocele (MMC), Dandy-Walker syndrome, holoprosencephaly, encephalocele. The survey showed a wide variation of outcome, with normal outcome 19%, slightly delayed 22%, moderately delayed 25%, severely delayed 28.5% and peri and postnatal death 5.5%. This variation seems to be determined by the basic disease and associated anomaly. A guideline for the diagnosis and treatment of fetal hydrocephalus is urgently required, which should be based on the analysis of the clinical data on each disorders and critical appraisal of reviews. Adult patients with congenital hydrocephalus are now increasing. The new issue on medical and social problems surrounding adult patients with congenital hydrocephalus should be discussed.

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Purpose : The purpose of the present study was to evaluate the availability of transcranial color-coded duplex sonography (TCDS) for detecting hemispheric hyperperfusion syndrome after carotid endarterectomy (CEA). Methods : This prospective study included 100 consecutive patients who underwent CEA for severe carotid stenosis. TCDS studies were serially performed to evaluate MCA flow velocity before and after CEA. Echo contrast agents were used when we could not detect MCA by conventional TCDS. Transoral carotid ultrasonography (TOCU) was also performed to evaluate the distal portion to the carotid stenosis before and 2 weeks after CEA. Regional CBF of MCA territory was evaluated quantitatively before and 4 and 14 days after CEA using single photon emission computed tomography (SPECT). Vasodilatory capacity was evaluated before CEA using SPECT with acetazolamide (ACZ) challenge. Results : By TCDS with echo contrast agents, we detected MCA in 90 (90%) among 100 patients. Twelve (13%) of them showed clinical symptoms of hyperperfusion syndrome after CEA. In patients with hyperperfusion syndrome, affected MCA mean flow velosity ratio (after CEA/before CEA) was higher than that in patients without hyperperfusion (2.19 ± 0.47 vs 1.28 ± 0.27 times, p<0.000l). All 12 patients with hyperperfusion syndrome had remarkable change (> 1.5 times) in MCA mean flow velocity at any time point 1 to 4 days after CEA. Affected MCA mean flow velosity ratio between before and 4 days after CEA were significantly correlated with that in rCBF(R=0.47, p < 0.0001). Symptomatic carotid stenosis (p < 0.05), severe carotid stenosis by NASCET method (p < 0.05), retrograde flow of the ophthalmic artery ipsilateral to CEA detected by cerebral angiography (p< 0.001), the narrow diameter of the ipsilateral distal carotid artery by TOCU (/><0.0l), and reduced ACZ reactivity (/>< 0.001) in the ipsilateral MCA territory all contributed to prediction of hyperperfusion syndrome. Multivariate analysis revealed that the grade of reduced vasodilatory capacity (OR ・ 0.13, 95% CI: 0.02-0.95) was an independent risk factor for hyperperfusion syndrome. Conclusions : TCDS with echo contrast agents is available for evaluation of hyperperfusion syndrome after CEA.

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